During the Middle Ages, parchment prepared from animal hides was highly valued by ancient scholars for its durability, but was costly to produce. A common practice was to scrape the original text from the surface of existing parchment, and then write new text in the original text's place. Commonly known as palimpsest texts, these manuscripts have served as valuable sources of ancient texts thought to have been lost. Often the incomplete recycling techniques used at the time and the acidic nature of some inks left faint indelible impressions on the parchment. These impressions are often referred to as “underwriting” or “underlayment”.
Early techniques by modern scholars to decipher the original text included simply reading the underwriting by eye, often under magnification. Later it was discovered that application of certain chemical reagents, such as hydrochloric acid, potassium cyanide or ammonium bisulfate, would make the underwriting text visible by chemically reacting with the ink used in the original text. However, use of these chemical techniques would often result in permanent damage to the parchment, and decomposition over time would render the palimpsest illegible.
Modern techniques now include the use of ultraviolet (“UV”) light and digital photography to decipher underwriting, without damaging the manuscript. Ultraviolet light enhances the contrast between the ink and the parchment because iron gaul ink was widely used in ancient manuscripts, and iron absorbs UV light. The parchment also absorbs UV light, but then fluoresces in the blue spectral region. When a palimpsest manuscript is exposed to UV light, the residual iron from the underwriting ink absorbs the UV light, while the parchment fluoresces a bluish color. The dark underwriting ink with a bluish colored parchment background often provides an effective contrast whereby the original text in the underwriting can be deciphered.
Early UV enhancement of contrast involved the use of full spectrum UV mercury arc lamps. However, these lamps often resulted in a user experiencing severe “welder's blindness” from prolonged exposure to high doses of UV radiation, and the use of full spectrum UV gave uneven contrast between the iron gaul ink and the parchment. The use of narrow spectrum ranges of UV light reduce the likelihood of welder's blindness, and also provides a more consistent UV enhancement of contrast between the ink and the parchment.
While the use of UV light has become very popular for analyzing ancient manuscripts, a drawback is that current archival imaging systems are not portable. To use UV light, the manuscripts must by physically removed from their archival locations and transported to the location of the imaging systems. Additionally, the manuscript has to be carefully packaged and transported, so the risk of potential physical damage and exposure to harmful environmental changes is high. Understandably, curators are reluctant to allow scholars to remove the manuscripts for UV imaging. Further, the cost of transportation and the cost of the commercial imaging systems is very high, precluding many individuals and scholars from using UV light to analyzing ancient manuscripts for underwriting.
Therefore, there is a need for a portable copystand having a UV light source that an individual can easily transport to an archival location and take digital images of UV light enhanced manuscripts.